Adsorption of ciprofloxacin from water: A comprehensive review

Abstract

Abstract In this paper, the adsorption of Ciprofloxacin (CIP) from water in studies over the last decade was reviewed. The purpose of this review is to analyse the vast body of literature on the subject, identify key empirical findings on specific investigation domains, establish knowledge gaps and grey areas that could serve as a foundation for other investigations by researchers and predict future perspectives in the research area. The highest reported adsorption capacity for CIP was 1564 mg/g for magnetic N-doped porous carbon. The major mechanisms of CIP uptake are electrostatic interactions, π-π interactions, H-bonds, hydrophobic interactions and pore diffusion. CIP uptake was best-fit to either the Langmuir and Freundlich isotherm and the pseudo-second-order kinetic model. For most adsorbent types, reusability of up to 4 cycles could be achieved with good retention of uptake capacity. The review further showed that CIP uptake in adsorption columns was majorly best fitted to the Thomas and Yoon-Nelson models. In competitive adsorption scenarios, the presence of other pharmaceuticals usually decreases the uptake of CIP. Looking to the future, studies on novel hybrid processes, adsorbent modification, composite adsorbent development, neural network modelling, molecular simulations and used adsorbent disposal techniques are likely to increase for CIP adsorption.